Sustainable transport in London
London’s zero-emission bus fleet also includes 20 hydrogen-powered fuel cell buses, introduced in 2020. 21 In the fuel cell, hydrogen is supplied to an anode, and air is supplied to a cathode. Hydrogen atoms are separated into protons and electrons by a catalyst in the electrolyte. The electrons enter an external circuit, generating an electric current to power the bus, while the protons bond with oxygen in the cathode to form water and heat. 22 As water and heat are the only by-products, these buses are zero- emission with very low levels of indirect carbon emissions. As such, if used more widely, hydrogen buses would certainly make London’s buses more environmentally sustainable. TfL’s rail systems are generally more environmentally sustainable than buses due to the full electrification of the network. A tram journey from East Croydon to Wimbledon was estimated to produce 0.4kgCO 2 e, three times less than London buses and less than electric cars (0.5kgCO 2 e). 23 On the Underground, CO 2 e emissions per passenger-kilometre have fallen from 59g in 2011 to 26g in 2022 – a 55% decrease. Similarly, CO 2 e emissions per passenger-kilometre on the DLR have fallen 57%, while Tramlink and London Overground have seen a 26% reduction in the same period. This reflects improved energy efficiency on the rail systems, aided by the replacement of old rolling stock. Further improvements could be seen as TfL rolls out LED lights on all new trains, starting with new Piccadilly line and DLR trains. 24 LED lights consume up to 40% less energy than fluorescent lights, so increased use of LED lights on the network should help improve energy efficiency. 25 Ultimately, journeys on London’s public transport network are more environmentally sustainable than private transport, and there is evidence to suggest that more people are choosing public transport over private transport. Convenience and connectivity Since 2001, the use of private transport has fallen, while public transport use has increased. An estimated 10 million daily journeys were made by private transport in 2019, down from 10.9 million in 2000. In that same period, public transport usage rose from 6.1 million to 9.7 million daily journeys. Between 2000 and 2019, the share of daily trips on public transport rose from 27% to 36%, while private transport use fell from 48% to 37%. According to TfL, the DLR extension to London City Airport in 2005 saved ‘around 120,000 taxi rides and 288,000 car journeys’, with ‘almost half of all passengers travelling to London City Airport’ using the DLR, 26 showing how improved public transport connectivity can reduce the need for private transport.
21 Transport for London, ‘Bus fleet audit’, 1. 22 U.S. Department of Energy, ‘Fuel Cell Basics’, accessed August 22, 2025, https://www.energy.gov/eere/fuelcells/fuel-cell-basics.
23 Department for Transport, ‘Transport and environment statistics: 2023 (2021 data)’. 24 Transport for London, ‘Safety, health and environment annual report 2023/24’, 46. 25 LEDVANCE, ‘LED vs. Fluorescent Tubes: Which is Right for You?’, April 17, 2022, accessed August 23, 2025, https://www.ledvanceus.com/blog/Pages/LED-vs-Fluorescent-Tube-Comparison-Chart.aspx. 26 Transport for London, ‘Annual report and statement of accounts for 2007/08’, 2008, 34, https://tfl.gov.uk/corporate/publications-and-reports/annual-reports-past-years.
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